The invention herein rests in the art of security validation apparatus. Heretofore, numerous devices have been known for testing the authenticity of a paper purported to be a valid note, security, currency, or the like. In many known devices a reticle is used for masking or matching a complementary grid pattern characterizing the valid paper; the reticle effectively being a negative of the grid pattern. However, in recent years highly sophisticated photocopy machines which are capable of reproducing such grid patterns have been developed. Such photocopy machines are capable of passing the reticle test, causing the validation apparatus to accept mere copies as valid paper. It is known that many paper securities are characterized by the presence of colored areas thereon. Since photocopies generally are of a black and white nature, a secondary test, testing for the presence of colored areas, would be desirable. Even those devices capable of reproducing color are generally not capable of accurate reproduction thereof. Further, those persons attempting to pass copies as originals would normally not be aware of the fact that a secondary test is being performed. Consequently, a secondary test sensing the presence of particular colored areas on a security would provide a significant supplement to the primary reticle test of security validation apparatus.
To further discriminate against invalid paper, it is preferable that certain areas of the paper be tested for the presence of various colors and the proportionate degree to which each of the various colors exist within the area. By testing these areas on a ratio basis, determining the relative amount of one color present with respect to another, the test becomes more difficult to pass and the test inherently compensates for the degradation of the quality of the paper due to wear or age while simultaneously compensating for a similar degradation in the testing device.